In a seven game series, even when you’re certain of how strong each team is, the odds aren’t easy to directly calculate. You have to account for every possibility and the homecourt alternating. However, when you do this, Miami’s chances are bleak.
Going into the series, I estimated San Antonio’s strength at +8.7 (they’d beat an average team on a neutral court by 8.7 points) and Miami’s at +5.1. Based on this formula for home win probability and a tweak to account for the increased power of homecourt advantage in the playoffs, this results in the following probabilities for all the possible outcomes (this is before the game one loss.) Overall, the odds for San Antonio were at 82.1%.
Naturally, after the strange game where electrolytes gained a national stage, those odds have increased. The Heat face a difficult path to another title. The Spurs now have 87.8% odds of winning the championship according to my numbers.
To be fair, we can also look at the odds if we assumed both teams were evenly matched. (This is generous given that the two teams appeared to be even last year, and this season San Antonio appears to be better and Miami worse.) Even if we give the Spurs a 60% chance at winning at home and the Heat the same, the Game 1 win means the Spurs have a roughly 75% at winning the series now. (For the curious, at the onset of the series if we had assumed the two teams were even at the same above splits of 60/40, the Spurs would have had a 53% chance at winning.)
And I could have gone with a more severe team rating for Miami. I calculated San Antonio and Miami’s rating in terms of point differential when their stars (Duncan, Parker, Ginobili; LeBron, Wade, Bosh) were all available for a game, as well. The odds change to 90.0%. It’s a slight change, but at this point every percentage point matters.
On the bright side, Miami still has a chance. The odds aren’t 0%. In the world of statistics, 5% is a conventional significance level (that’s putting things simply, of course.) Statistically, Miami’s odds are not insignificant — there’s something worth fighting for here. If they can steal game two, the series odds for the Spurs drop to 69.3%. If you believe the Heat are a bit stronger than their point differential suggests, you can reasonably say the odds would be 50% at that point.
The NBA is still unpredictable. All it takes is one game to change the series. One game and history is written differently.